Split case seals and methods

Abstract

A turbomachine has a number of interspersed stages of rotor blades and stator vanes. A split case has first and second case sections meeting along a junction extending essentially along a longitudinal first plane. The metallic spring seal extends along the junction. The spring seal may be installed in a remanufacturing of an existing turbomachine.

1 . A turbomachine comprising: 
 a plurality of stages of rotor blades;    a plurality of stages of stator vanes interspersed with the stages of rotor blades;    a split case having first and second case sections meeting along a junction extending essentially along a longitudinal first plane; and    a metallic spring seal extending along the junction.    
   
   
       2 . The turbomachine of  claim 1  being a steam turbine.  
   
   
       3 . The turbomachine of  claim 1  being a stationary gas turbine.  
   
   
       4 . The turbomachine of  claim 1  driving an electrical generator.  
   
   
       5 . The turbomachine of  claim 1  wherein: 
 the metallic spring seal is a coil spring-energized c-seal segment.    
   
   
       6 . The turbomachine of  claim 1  wherein: 
 the first plane is horizontal;    the junction includes first and second junction sections respectively along opposite sides of a vertical longitudinal centerplane of the turbomachine; and    the metallic spring seal comprises first and second seal segments accommodated in an upward-facing channel in the first case section, respectively along the first and second junction sections.    
   
   
       7 . The turbomachine of  claim 1  wherein: 
 the metallic spring seal has an essentially uniform cross-section along a seal centerline; and    the seal centerline extends essentially in a second plane, parallel to the first plane, the seal centerline being non-straight to accommodate a change in stage diameter along the case.    
   
   
       8 . The turbomachine of  claim 1  wherein: 
 the first plane intersects a turbomachine central longitudinal axis.    
   
   
       9 . A turbomachine case seal comprising: 
 a c-sectioned jacket extending from a first end to a second end; and    an energizing spring within the jacket.    
   
   
       10 . The turbomachine case seal of  claim 9  wherein: 
 the energizing spring is a coil spring essentially sharing a centerline with the jacket;    the centerline has a at least one curve; and    the jacket consist essentially of a single metallic piece of a nickel-based superalloy.    
   
   
       11 . The turbomachine case seal of  claim 10  wherein: 
 the centerline has a plurality of straight portions.    
   
   
       12 . The turbomachine case seal of  claim 10  wherein: 
 the centerline has a plurality of straight portions joined at bends.    
   
   
       13 . The turbomachine case seal of  claim 10  compressed between mated flanges of a split turbine case.  
   
   
       14 . A method for modifying a turbomachine split case, the case comprising first and second case sections meeting along a junction extending essentially along a longitudinal first plane, the method comprising: 
 separating the first and second case sections along the junction;    machining a channel in the first case section along the junction;    inserting a metallic spring seal segment in the channel; and    reassembling the first and second case sections to compress the spring seal segment.    
   
   
       15 . The method of  claim 14  performed on the turbomachine after use of the turbomachine.  
   
   
       16 . The method of  claim 14  leaving the second case section essentially unaltered.  
   
   
       17 . The method of  claim 14  further comprising shaping the metallic spring seal segment to fit the channel.  
   
   
       18 . The method of  claim 14  performed on an industrial gas turbine.  
   
   
       19 . The method of  claim 14  wherein the reassembling causes contact between flanges of the first and second case sections.  
   
   
       20 . The method of  claim 14  wherein: 
 the channel is a first channel along a face of a first flange of the first case section;    the metallic spring seal segment is a first metallic spring seal segment; and    the method further includes: 
 machining a second channel in the first case section along the junction along a face of a second flange of the first case section;  
 inserting a second metallic spring seal segment in the second channel.  
   
   
   
       21 . A method for reengineering the configuration of a turbomachine split case, the case comprising first and second case sections meeting along a junction extending essentially along a longitudinal first plane, the method comprising: 
 adding a channel in the first case section along the junction; and    adding a metallic spring seal segment in the channel.